Backtrace on series format

[freimer]

Describe the bug
Receive backtrace on series type format string

To Reproduce
Specify a format string of "%Y-%m-%d %H:%M:%S%Z"

1. Schema (if applicable)

{
      "type": "series",
      "format": "%Y-%m-%d %H:%M:%S%Z",
      "incrementing": { "start": "2023-01-01 09:00:00", "increment": "1h" }
}

2. See error

thread 'main' panicked at 'a Display implementation returned an error unexpectedly: Error', /rustc/c5d82ed7a4ad94a538bb87e5016e7d5ce0bd434b/library/alloc/src/string.rs:2537:14
stack backtrace:
   0: rust_begin_unwind
             at /rustc/c5d82ed7a4ad94a538bb87e5016e7d5ce0bd434b/library/std/src/panicking.rs:575:5
   1: core::panicking::panic_fmt
             at /rustc/c5d82ed7a4ad94a538bb87e5016e7d5ce0bd434b/library/core/src/panicking.rs:65:14
   2: core::result::unwrap_failed
             at /rustc/c5d82ed7a4ad94a538bb87e5016e7d5ce0bd434b/library/core/src/result.rs:1791:5
   3: <synth_core::graph::series::SeriesFormatter<S> as synth_gen::generator::Generator>::next
   4: <synth_gen::generator::try::TryOnce<G> as synth_gen::generator::Generator>::next
   5: <synth_core::graph::series::SeriesNode as synth_gen::generator::Generator>::next
   6: <synth_core::graph::Graph as synth_gen::generator::Generator>::next
   7: <synth_gen::generator::Concatenate<Left,Right> as synth_gen::generator::Generator>::next
   8: <synth_gen::generator::Concatenate<Left,Right> as synth_gen::generator::Generator>::next
   9: <synth_gen::generator::Chain<G> as synth_gen::generator::Generator>::next
  10: <synth_gen::generator::Brace<BG,G,EG> as synth_gen::generator::Generator>::next
  11: <synth_core::graph::object::ObjectNode as synth_gen::generator::Generator>::next
  12: <synth_core::graph::Graph as synth_gen::generator::Generator>::next
  13: <synth_gen::generator::Repeat<G> as synth_gen::generator::Generator>::next
  14: <synth_gen::generator::Brace<BG,G,EG> as synth_gen::generator::Generator>::next
  15: <synth_gen::generator::try::AndThenTry<TG,F,O> as synth_gen::generator::Generator>::next
  16: <synth_core::graph::Graph as synth_gen::generator::Generator>::next
  17: <synth_gen::generator::Concatenate<Left,Right> as synth_gen::generator::Generator>::next
  18: <synth_gen::generator::Chain<G> as synth_gen::generator::Generator>::next
  19: <synth_gen::generator::Brace<BG,G,EG> as synth_gen::generator::Generator>::next
  20: <synth_core::graph::object::ObjectNode as synth_gen::generator::Generator>::next
  21: <synth_core::graph::Graph as synth_gen::generator::Generator>::next
  22: synth_gen::generator::Generator::complete
  23: synth::sampler::Sampler::sample_seeded
  24: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
  25: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
  26: std::thread::local::LocalKey<T>::with
  27: <core::future::from_generator::GenFuture<T> as core::future::future::Future>::poll
  28: async_io::driver::block_on
  29: async_global_executor::executor::block_on
  30: std::thread::local::LocalKey<T>::with
  31: std::thread::local::LocalKey<T>::with
  32: async_std::task::builder::Builder::blocking
  33: synth::main

Expected behavior
That it would not panic and provide an appropriate error message.

Screenshots
Not necessary

Environment (please complete the following information):

• OS: Linux
• Version: Ubuntu 22.04

Additional context
Add any other context about the problem here.

[freimer]

It also throws errors, "input contains invalid characters" although not backtraces, simply by removing the dashes between %Y-%m-%d in the format string. Sorry, I have to move on to something else.